Signal Processing Stack Exchange
Signal Processing Stack Exchange

Questions tagged [local-features]

81 questions
75
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4 answers

What are some free alternatives to SIFT/ SURF that can be used in commercial applications?

As far as I understand, both SURF and SIFT are patent protected. Are there any alternative methods that can be used in a commercial application freely? For more info on the patent check…
Andrey Rubshtein
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17
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5 answers

Scale and Rotation invariant feature descriptors

Can you list some scale and rotational invariant feature descriptors for use in feature detection. The application is for the detection of cars and humans in video captured by a UAV, using a multi-class classifier. So far I have been looking at SIFT…
Jono Brogan
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15
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2 answers

Image Registration by Segmentation

Image registration algorithms are usually based on point features such as SIFT (Scale-Invariant Feature Transform). I saw some references to line features, but I was wondering if it would be possible to match image segments instead of points. For…
Libor
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15
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1 answer

What is the difference between feature detectors and feature descriptors?

What is the difference between feature detectors and feature descriptors? Which among these are detectors and which are descriptors: Harris, SURF, Min Eigen, FAST, SIFT, BRISK
Jayesh Parmar
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15
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1 answer

Detection of circles (ellipses) in 2D point cloud

Given a set of points (2D) i.e., point cloud (PC), the question is about a robust, accurate and computing-friendly method to find circles (or ellipses in advanced version). The intuitive idea is to use Brute-Force Search on all possible points (as…
Developer
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15
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1 answer

Binary robust independent elementary features ("BRIEF") understanding

How are the descriptors in the BRIEF algorithm matched to each other? How is the template image found in the another image? How do we compare the descriptors? I have read that article but didn't understand how they have done it. They wrote that they…
maximus
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4 answers

What Kind of Features Can I Extract from a Signal

I want to monitor (automatic-)gearbox failures on some vehicles. For each vehicle I have a captured signal representing the selected gear at each one millisecond. An example of two signals are shown on the figure bellow. I would like to compute…
eLearner
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10
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2 answers

How Hessian feature detector works?

I know about Harris corner detector, and I understand the basic idea of its second moment matrix, $$M = \left[ \begin{array}{cc} I_x^2 & I_xI_y \\ I_xI_y & I_y^2 \end{array} \right]$$, edges and other unstable points can be removed via $M$. But…
avocado
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9
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2 answers

Image Processing Prior to Feature Detection

I have implemented a feature detector based on Harris corners. It works fine most times, but there are cases where it performs poorly. I need to make it work on many different images without configuring it individually. The problem is with the…
Libor
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9
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1 answer

Good features / algorithms for recognizing car-models in images

I have a question concerning object recognition, especially recognizing car-models! I am at the beginning of a work about identifying the same car-model in different images. At the moment I think one of the best algorithm for 3D object recognition…
jstr
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8
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1 answer

Suggested Preprocessing methods for OCR on Circular Images

Hello this is my sample image I am going to do real time character detection on images like that. I've tried SURF, SIFT, MSER and template matching on original image without any preprocessing. I can detect characters but when the image changes this…
Anar Bayramov
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8
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1 answer

Feature extraction/reduction using DWT

For a given time series which is n timestamps in length, we can take Discrete Wavelet Transform (using 'Haar' wavelets), then we get (for an example, in Python) - >>> import pywt >>> ts = [2, 56, 3, 22, 3, 4, 56, 7, 8, 9, 44, 23, 1, 4, 6, 2] >>>…
theharshest
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8
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4 answers

Preprocessing to improve Harris corner tracking between video frames?

In our unmanned aerial vehicle grayscale video image stabilization application, we're having difficulty finding the "good" Harris corners in frame N+1 selected from frame N. The source of the difficulty appears to be radical nonuniform pixel…
David Pointer
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8
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Purpose of image feature detection and matching

I'm a new guy in image processing and computer vision, so this question might be stupid to you. I just learned some feature detection and description algorithms, such as Harris, Hessian, SIFT, SURF, they process images to find out those keypoints…
avocado
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5
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Filtering Corners Detected on Multiple Scales

I made a multi-scale Harris corner detector (inspired by MOPS) which is simply a Harris corner detector performed on several scales (i.e. subsampled versions of the same image). This effectively make the detector more robust to noisy/blurred images…
Libor
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